Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
cam thuc » am thuc, nam thuc, cam thu
hanh dai » hanh tai, hanh dao, vanh dai
tu sach » thu sach, su sach, te sach
vu sach » vu bach, su sach, vu khach
hoc cac » hoc cao
nang ma » tang ma, sang ma, nang cao
van cam » van nam, van lam, van cau
thuc va » thuc vat, thuc dan, thuc day
va hanh » van hanh, va thanh, va danh
ma hoi » mai hoi, xa hoi, ma hoa
cua te » cua tu

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((((tu sach) or (vu sach))) or (hoc cac)) ky nang ma hoi. hieu van cam thuc va hanh dai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((((tu sach) OR (vu sach))) OR (hoc cac)) ky nang ma hoi. hieu van cam thuc va hanh dai cua te.
• Adding a wildcard symbol may retrieve word variants: ((((tu sach) or (vu sach))) or (hoc cac)) ky nang ma hoi. hieu van cam thuc va hanh dai cua te*.